Poland's Communist authorities today issued a high-level public warning to reject an underground call for May Day demonstrations as newspapers carried front-page announcements that "military operation groups" will be deployed throughout the country for one week beginning Wednesday.

As political tensions mounted, former Solidarity chairman Lech Walesa was questioned by police for the second day running and the third time in a week.

Government spokesman Jerzy Urban told reporters the military units "are to perform strictly peaceful tasks, namely as before, to control the provincial economy, which is quite often neglected." Such groups appeared for the first time on Oct. 26, 1981, to be followed on Dec. 13 by declaration of martial law.

In a related development, authorities announced the "temporary arrest" of former Solidarity national spokesman Janusz Onyszkiewicz on charges of participating in "underground structures" and preparing for the May Day demonstrations.

A mathematics lecturer at Warsaw University, the 45-year-old Onyszkiewicz has been in police detention since Sunday after a speech at the memorial to the Warsaw Ghetto in which he linked the ideals of those who died in the uprising 40 years ago with Solidarity's ideals. The announcement of his arrest said detailed plans for May Day activities were found in his home and office along with other illegal publications during a police search yesterday.

Meanwhile, a solemn day of authorized wreath-laying to mark the anniversary of the ghetto uprising was marred for participating Jews when a representative of the Palestine Liberation Organization was permitted to lay flowers at the memorial to the Jewish resistance fighters.

Fouad Yaseen, head of the PLO's accredited mission in Warsaw, said when asked by reporters why he was joining the ceremony, "The Jewish people, including those heroes of the ghetto, were victims of Hitler's nazism and Palestinians are victims of the new Nazis. . .Zionist Israel."

Tel Aviv Mayor Shlomo Lahat, the senior Israeli politician present, accused the Polish government of violating an assurance that the PLO would not come to the monument today.

Reuter quoted Israeli radio as saying Education Minister Zevulun Hammer ordered Israeli delegates to leave for home in protest.

A communique published after a joint meeting of the ruling Communist Party Politburo and the government Presidium condemned underground forces for "making a desperate adventurist attempt" to stir trouble and thwart the gradual "process of normalization" of Polish life, reflected in official plans to welcome Pope John Paul II in June.

Noting last week's call by the leading underground group--the Provisional Coordinating Committee of Solidarity--to boycott official May Day events and organize independent rallies, the statement warned that security forces would act "decisively" to prevent trouble, and urged people to "display a responsible attitude in this situation" and "reject the attempt at sowing unrest."

In Gdansk, Walesa was summoned to police headquarters and held for 3 1/2 hours for an interrogation that the labor leader said afterwards had dealt mainly with the whereabouts of missing Solidarity union funds in Wroclaw.

The money, said by authorities to total 80 million zlotys (nearly $1 million), was hidden by Jozef Pinior, then Wroclaw regional treasurer for Solidarity, reportedly to avoid confiscation by Communist officials during the 1981 military crackdown. Pinior is one of five members of the Provisional Coordinating Committee. Walesa and the underground leadership announced last week they had met on the weekend of April 9.

After sessions yesterday and last week, "this time they changed their tactics," Walesa, 39, said. "If they intend to question me on the activities of each of Solidarity's 10 million members, then I'll be kept busy until my dying day."

Walesa has remained silent about the details of his meeting with the underground, but has called a press conference for Wednesday.

Urban said the union activist had been intercepted yesterday and detained by police as he drove from Gdansk to Warsaw to be sure he would be in Gdansk for today's interrogation and wouldn't be doing anything illegal in the meantime.

"Walesa is not forbidden to leave Gdansk," said the spokesman, "but the task of the militia is to prevent illegal acts." Walesa had intended to come to Warsaw to lay flowers in memory of the ghetto uprising.

Responding to a rise in opposition activity, the government paper Rzeczpospolita today published a front-page commentary denouncing underground "extremists" for renewing their protest drive and embarking once again on "a path of demonstrations and street clashes." Their aim, said the paper, is to show Poland to the world as "still a restless country" and thus prompt the Vatican to "reconsider the purposefulness" of a papal pilgrimage in June.

The government and the opposition have accused each other of planning provocations that will force cancellation of the papal visit.

Talking to reporters, Urban said that demonstrations in the next two months would "complicate the situation and worsen conditions for the visit." But he seemed to want to avoid an escalation of threats, adding: "Nevertheless, we do not expect any such disturbances here in Poland that could undermine the pope's wish to come."

In what appeared to be both a word of caution to Walesa and an attempt to implicate him in the planned demonstrations, the commentary in the government paper referred to his statement that the meeting with underground leaders had been to coordinate strategies and asked: "Would this mean that Walesa took on himself the risk of responsibility for the results of urging confrontation?"

The heightened tensions between Communist authorities and former Solidarity leaders have provided a jarring backdrop for the 750 foreign Jews attending this week's elaborate commemoration program for the 40th anniversary of the Warsaw Ghetto uprising.